Process of producing fermentable sugar from lignocellulose.



certain process or series of steps tending to UNITED STATE 8 P glENT OFFICE.

MALCOLM F. lEWEN AND GEORGE H. TOMLINSON, OF CHICAGO, ILLINOIS, ASSIGNORS TO STANDARD ALCOHOL COMPANY, OF MAINE.

' No Drawing.

To all whom it may concern Be it known that we, MALCOLM F. EWENf a citizen of the United States, and :GnoncE' H. ToMLINsoN, a subject of the King of England, residing at Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful Improvement in the Process of Producing Fermentable Sugar from Lignocellulose, of which the following is a specification.

Our invention relates to a process of pro ducing fermentable sugar from ligno-cellulose, particularly from comminuted lignocellulose, and has for its object to provide a greatly economize the cost of production.

It is well knownthat fermentable sugar can be produced from ligno-cellulose, such as sawdust, by the application of certain acids thereto, and the treatment of the mixture in what is known as a digester. with heat and under'pressure. The capacity of a plant for thus producing fermentable' sugar is limited by the capacity of the digesters. The digester is an important and essential part of the apparatus, and also a part which is expensive both to erect and to operate. Ifthe digester is idle for any given period, or its period of activity and effective operation is shortened,-to that extent the capacity of the entire plant is re duced and the cost of production increased. It will readilybe seen that considerations of 'this nature are of great importance in view of the tact that we are dealing with very large quantities otligno-eellulose which produce relatively small percentages of fer- 'mentable sugar. It is highly necessary, t therefore, that the plant be operated in connection with a process which permits the utilization of the entire plant to the highest degree at all timesv It is such limitations as these suggested which have assisted in; rendering eii'orts to commercially produce sugar from ligno cellulose in the past, partly unsuccessful. g The best processes are those in which a limited amount of acid is applied to a large amount? of comminuted gnu-cellulose and,

Specification oi lletterai'atent. Application filed November 12, 1810. Serial No. 592,066.

NEW YORK, N. Y., CORPORATION OF PROCESS OF PRODUCING FERMENTABLE SUGAR FROM LIGNOCELLULOSE.

Patented July 16, 19i2.

j owing to the nature of the material and intiniate mixture of the acid therewith which is so highly desirable for uniform and etficlent operation, is'extremely difiicult. The mixture of the acid with the sawdust (which is a form of material very commonly used) has been effected by forcing the acid into the digester after the sawdust has been. placed therein, also by forcing the acid into the digester at the time when the sawdust is supplied thereto, also by. discharging or spraying the acid into the stream of sawdust; as it passes toward or into the digester, and also by spraying the acid into the stream of sawdust as it moves along in the trough or passage or receptacle which leads to the digester; and doubtless there are other methods which have been tried. All these involve, as experience shows,'a eat'deal of'loss of time in the active period of the digester. These several methods involve delay because the supply of the material to the digester is retarded because of the necessity of mixing the acid with the sawdustas the latter moves toward the digester, or because of the use of the digester itself as a mixing chamber. It takes time to effect the mix ture in question;

Our invention, therefore, comprises first: mixing the acid with the saw dust, apart from the digester, and this maybe done in anyldew stream, the entire required amount of sawv I dust and acid into the digester, without delay i1icident 'to mixing, orretarding the stream because of mixing. In ordinary practige it frequently requires as much as twenty minutes to fill the digester with a comparatively slow moving or small stream of mixed material or material to be mixed in the digestcr; whereas, if the completely and satisfactorily mixed sawdust can be discharged (17L nmssc into the digester, the latter can be filled in as little as five minutes. The difierenee between these two periods of filling is of immense importance in the ordinary operation of such a plant, as will be seen when it is remembered that the digest ing operation proper requires about forty minutes time. The total operation under ordinary conditions, therefore, from begin ning to. fill to discharging, would be about sixty minutes; whereas, under the present process, it is'about forty-five minutes. Under such circumstances, the increase would be twenty-five per cent. efliciency.

Our invention comprises third: the heating of the sawdust, it' that should be found, under the conditions of any particular plant, desirable betore. it is introduced into the digcstcr. lVhcn the sawdust is introduced iua heated state the conversion can begin at once, and the time of treatment in the digester is correspondingly reduced.

The-advantage of our process is further shown by the fact that the digester itself has no opportunity to cool oil, for, in a continuousiy operating plant, the moment the digester discharges its digested material it should, while in its heated condition, be in stantly re-charged and set in motion to carry out the digesting process on the new charge. The cooling oi the digester incident to the slow process of filling the same under the old methods employedt' is disastrous to a.

certain extent, because it is the cooling and heating of the digester which tends to destroy it. As ckperience has shown hercto-- 'l'ore, these. digesters are made of various kinds of n'iaterials, and heatin and cooling tend to cause the materials of which the digcster is composed to break and leak; whereas, under the conditions of our process, they 1 remain intact. The time required for mixing the sawdust and the acid, under the con ditions of our process, may be as much as convenience may require. but in no event does it fatl'ect the time of operation in the digester,-the two processes being entirely separate. The digestcr; in ordinary practice, is ot course hot at the time when it has discharged its digested contents, and is ready to rece ve a new charge. Being hot,

it is desirable to introduce the charge,- comcomminuted lign'o-celluloseas distinguished from its slow introd action by a feeble stream.

it, on the other hand, the sawdust be dischargei'l en 92211350 or quickly into the digester without having been mixed with the acid, while the supply of oxygen may be adequate, the diilicrities of eifecting the mixture within the digester, and the delaysincident thereto, then confront us.

1. The process of producing ferment-able sugar from comminuted hgno-cellulose, which consists in mixing thcligno-cellulose' with a limited amount of a hydrolyzing acid, apart from the digester, then discharging the mixed acid and ligno-eellulose intethe digester quickly, the'n closing the digester and subjecting the contents to the required heat and pressure until the sugar has been 'formed, then discharging the contents from 5 the digestcr and recovering the sugar in any desired manner.

2. The process of producing terinentable sugar from coin'minuted 'ligno-cellulose, which consists in mixing the ligno-cellulose. with a limited aniountot' a. hydrolyzing acid, apart from the digester, then discharging the mixed. acid and l'igno-cellulose into the digester while the latter is heated, quickly, then closing the digester and subjecting the contents to the required heat and pressure until the sugar. has been torn'ied, then discharging the contents from the digester, then filling the heated digester with another charge of the mixed lignocellulose and acid, delivered thereto quickly, and so continuing the process.

3.'The process of producing fermentable sugar from comn'iinutec'l ligno-cellulose, which consists in mixing the ligno-eellulose with a limited amount of a hydrolyzing acid, apart from the digester, then discharging the mixed acid and ligno-cellulose into the digester quickly, then closing the digester and subjecting the contents to the required heat and pressure until the sugar has been formed, then discharging the contents from the digester and recovering the sugar in any desired manner.-the mixture or ligno-cellulose and acid being heated before it is 1 5 introduced into the digester.

4. The process of producing fcrmentable sugar from comminuted ligno-cellulose, which consists in mixing the ligno cellulose with alimited amount of a. hydrol as; acid, apart from the digester, thendii urging the mixed acid and ligno-eellulo into the digestcr while the latter is hea quic ly, then closing the digester and subjecting 'r. contents to the required heat and pre until the sugar has been formed, then u. charging the contents from the digest then titling the heated digester with ane charge of the mixed ligno-cellulose and tC'L delivered thereto quickly, and so continw izw' the gn'0u0ss,-ihu mixture of lign0-cclconsists in pro-boating Hui mass before inlmmc and mud bump; heated before 1t 1s troducmg 1t min the dlgvster.

iniwnmvud into Um (ligester. I MALCOLM I. EVE N.

5. In a process of producing fermentable GEORGE H. '1. OMLINSON. 5 mum].- i'rnm mmminutcd ligno-clluldse 01' \Vitncsscs:

nihm: rullnlusic raw material by digestion ERNEST S HALL, with a hydrnlyzing agent, the stefj which A. 0. WEN-11c. 

